Bolt Circle Diameter Module:
Finding the Bolt Circle Diameter from Chord Length

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  Bolt Circle Diameter Lesson
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Geometer's Sketchpad Tutorial

These are the basics that you need to know to the do the Bolt Circle Diameter Module. As a general rule, to select multiple items hold the shift key down.

To drag a point to a new location - With the mouse, click on the point you want to move. A black circle will surround the point. This means the point is now selected. While holding the mouse button down, move the selected point to the desired location.

To measures distances - Select one of the points then, while holding the shift key down, select the other point. Go up to the Measure menu and Distance will be highlighted. If not then you need to reselect the points. Select Distance and the measurement will appear on the screen.

To measures angles - Select the three points of the angle you are trying to measure. For example, if we want to measure <EADG, you have to select the points IN ORDER. In other words, you can select points E, then A and then D or points D then A, then E. The angle you are measuring has to be the point in the middle. Go up to the Measure menu and Angle should be highlighted. If not reselect the figure. Click on Angle and the measurement will appear on the screen.

To calculate - To do calculations, select the measurements that are involved in the calculation. Remember, to select multiple measurements, hold the shift key down. Go up to the Measure menu and select Calculate.... A little calculator will appear. Use the keypad to enter numbers and basic operations (+,-,*,/). The measurements you selected are under the Values menu. You can select the appropriate measurement when necessary. Under the Function menu, functions such as square root and trig functions are located. After you finish inputting your calculation, click O.K. and the result will appear on the screen.

To get more practice, open a blank sketch and draw some triangles and get some practice measuring angles, lengths and performing calculations.

-Back to Problem Statement-  -Go to Lesson Worksheet 1-